// © Broadcom. All Rights Reserved.
// The term “Broadcom” refers to Broadcom Inc. and/or its subsidiaries.
// SPDX-License-Identifier: Apache-2.0

package toolbox

import (
	"bytes"
	"fmt"
	"net"

	xdr "github.com/rasky/go-xdr/xdr2"
)

// Defs from: open-vm-tools/lib/guestRpc/nicinfo.x

type TypedIPAddress struct {
	Type    int32
	Address []byte
}

type IPAddressEntry struct {
	Address      TypedIPAddress
	PrefixLength uint32
	Origin       *int32 `xdr:"optional"`
	Status       *int32 `xdr:"optional"`
}

type InetCidrRouteEntry struct {
	Dest         TypedIPAddress
	PrefixLength uint32
	NextHop      *TypedIPAddress `xdr:"optional"`
	IfIndex      uint32
	Type         int32
	Metric       uint32
}

type DNSConfigInfo struct {
	HostName   *string `xdr:"optional"`
	DomainName *string `xdr:"optional"`
	Servers    []TypedIPAddress
	Search     *string `xdr:"optional"`
}

type WinsConfigInfo struct {
	Primary   TypedIPAddress
	Secondary TypedIPAddress
}

type DhcpConfigInfo struct {
	Enabled  bool
	Settings string
}

type GuestNicV3 struct {
	MacAddress       string
	IPs              []IPAddressEntry
	DNSConfigInfo    *DNSConfigInfo  `xdr:"optional"`
	WinsConfigInfo   *WinsConfigInfo `xdr:"optional"`
	DhcpConfigInfov4 *DhcpConfigInfo `xdr:"optional"`
	DhcpConfigInfov6 *DhcpConfigInfo `xdr:"optional"`
}

type NicInfoV3 struct {
	Nics             []GuestNicV3
	Routes           []InetCidrRouteEntry
	DNSConfigInfo    *DNSConfigInfo  `xdr:"optional"`
	WinsConfigInfo   *WinsConfigInfo `xdr:"optional"`
	DhcpConfigInfov4 *DhcpConfigInfo `xdr:"optional"`
	DhcpConfigInfov6 *DhcpConfigInfo `xdr:"optional"`
}

type GuestNicInfo struct {
	Version int32
	V3      *NicInfoV3 `xdr:"optional"`
}

func EncodeXDR(val any) ([]byte, error) {
	var buf bytes.Buffer

	_, err := xdr.Marshal(&buf, val)
	if err != nil {
		return nil, err
	}

	return buf.Bytes(), nil
}

func DecodeXDR(buf []byte, val any) error {
	r := bytes.NewReader(buf)
	_, err := xdr.Unmarshal(r, val)
	return err
}

func NewGuestNicInfo() *GuestNicInfo {
	return &GuestNicInfo{
		Version: 3,
		V3:      &NicInfoV3{},
	}
}

func (nic *GuestNicV3) AddIP(addr net.Addr) {
	ip, ok := addr.(*net.IPNet)
	if !ok {
		return
	}

	kind := int32(1) // IAT_IPV4
	if ip.IP.To4() == nil {
		kind = 2 // IAT_IPV6
	} else {
		ip.IP = ip.IP.To4() // convert to 4-byte representation
	}

	size, _ := ip.Mask.Size()

	// nicinfo.x defines enum IpAddressStatus, but vmtoolsd only uses IAS_PREFERRED
	var status int32 = 1 // IAS_PREFERRED

	e := IPAddressEntry{
		Address: TypedIPAddress{
			Type:    kind,
			Address: []byte(ip.IP),
		},
		PrefixLength: uint32(size),
		Status:       &status,
	}

	nic.IPs = append(nic.IPs, e)
}

func GuestInfoCommand(kind int, req []byte) []byte {
	request := fmt.Sprintf("SetGuestInfo  %d ", kind)
	return append([]byte(request), req...)
}

var (
	netInterfaces = net.Interfaces
	maxNics       = 16 // guestRpc/nicinfo.x:NICINFO_MAX_NICS
)

func DefaultGuestNicInfo() *GuestNicInfo {
	proto := NewGuestNicInfo()
	info := proto.V3
	// #nosec: Errors unhandled
	ifs, _ := netInterfaces()

	for _, i := range ifs {
		if i.Flags&net.FlagLoopback == net.FlagLoopback {
			continue
		}

		if len(i.HardwareAddr) == 0 {
			continue // Not useful from outside the guest without a MAC
		}

		// #nosec: Errors unhandled
		addrs, _ := i.Addrs()

		if len(addrs) == 0 {
			continue // Not useful from outside the guest without an IP
		}

		nic := GuestNicV3{
			MacAddress: i.HardwareAddr.String(),
		}

		for _, addr := range addrs {
			nic.AddIP(addr)
		}

		info.Nics = append(info.Nics, nic)

		if len(info.Nics) >= maxNics {
			break
		}
	}

	return proto
}

func GuestInfoNicInfoRequest() ([]byte, error) {
	r, err := EncodeXDR(DefaultGuestNicInfo())
	if err != nil {
		return nil, err
	}

	return GuestInfoCommand(9 /*INFO_IPADDRESS_V3*/, r), nil
}
